Present-day vehicles, such as passenger cars, trucks and trains, are often equipped with alerting or assisting systems which alert the driver to dangerous situations or which may operate the breaks, throttle or steering system when a collision is imminent. A commonly used road vehicle assist system is ABS (Anti-lock Braking System), which regulates braking when the wheels of the vehicle are locking. Another example is parking assistance, which produces a warning signal when the distance to another vehicle or object becomes small. All these systems require sensors which gather information regarding, for example, the speed of the vehicle, the rotational speed of the wheels, the outside temperature, and/or the distance to other objects.
It is of course essential that these vehicle alerting and assistance systems and their sensors work accurately and reliably under all circumstances. Extensive testing of the systems in all possible situations is therefore required. Various systems have been devised to allow the testing of vehicle alerting and assistance systems.
U.S. Pat. No. 7,013,704 (Kusters et al./TNO) discloses a system for testing a vehicle or a vehicle component. The system comprises a test stand on which the vehicle or vehicle component can be positioned, a movable platform or undercarriage on which an object can be positioned, and a control computer to control the movements of the undercarriage. The vehicle or vehicle component comprises at least one sensor while the vehicle may be provided with an “intelligent” system. The undercarriages, which may carry actual vehicles, dummy vehicles or other objects, each have four wheels which can all be both driven and steered. This allows the undercarriages and the vehicles they carry to freely move over a test road surface and to perform various manoeuvres. The test stand, which is controlled by a central control computer, allows the vehicle being tested to make various rotational movements and to simulate the effects of road friction, vehicle mass and other factors.
Although the system of U.S. Pat. No. 7,013,704 is very useful to simulate various manoeuvres, it is less suitable for simulating (near-)collision situations. The undercarriages are incapable of decelerating quickly. If an undercarriage approaches the vehicle being tested at a high speed, it has to slow down relatively early, make an evasive movement, or collide with the vehicle. Slowing down early or making an evasive movement makes it impossible to study a vehicle safety system during the crucial last second before impact, while colliding with the vehicle obviously causes both the vehicle being tested and the undercarriage (including the vehicle being carried by the undercarriage) to be damaged, thus significantly increasing the cost of the test.
In addition, in the test system of U.S. Pat. No. 7,013,704 other objects (placed on undercarriages) can manoeuvre relative to the vehicle being tested. Although the test stand allows to measure the effects of vehicle rotations (yaw, pitch, roll) and vehicle mass on the sensor measurements, the system does not take the effects of braking or acceleration of the vehicle on the relative speed and distance to the undercarriages into account. Accordingly, the possibilities of performing realistic (near-)collision tests are necessarily limited.
U.S. Pat. No. 6,023,984 (Mazur et al./Breed Automotive) discloses a test apparatus for testing occupant sensors in a vehicular safety restraint system. The test apparatus comprises a stationary sensor and a “crash sled”: a movable sled capable of sliding on a support. The sled can be accelerated and decelerated by a DC motor and/or springs. This known test apparatus simulates the movement of the occupant of a vehicle but is not capable of taking the actual dynamic behaviour of the vehicle into account. Neither is it capable of sensing objects outside the vehicle.